For correct diagnosis of various cancer diseases biopsies are taken. This can either be via a lumen of an endoscope or via needle biopsies. An example of a needle biopsy is shown in FIG. 1, where a biopsy is taken from the prostate via the rectum. In order to find the correct position to take the biopsy, various imaging modalities are used such as X-ray, MRI and ultrasound. In case of prostate cancer in most cases the biopsy is guided by ultrasound. Although helpful, these methods of guidance are far from optimal. The resolution is limited and, furthermore, these imaging modalities can in most cases not discriminate between benign and malignant tissue. As a result one does not know for certain that from the correct part of the tissue a biopsy is taken. The biopsies are almost blind biopsies and even if after inspection of the tissue no cancer cells are detected, it is not known for certain that one did not simply miss the right spot to take the biopsy. Accordingly, since these biopsies are performed without direct feedback this procedure is prone to errors.